Image Collage Maker

How the Image Collage Maker creates browser-only photo collages from multiple image aspect ratios.

Last updated: May 31, 2026 Try this tool

What It Does

Image Collage Maker combines multiple local images into one exported collage. Drop images into the tool, choose an output ratio, adjust spacing and fit behavior, drag shared dividers when needed, then download the result as PNG, JPG, or WebP.

Key Features

  • Automatic layouts - Generates a balanced collage from each image’s aspect ratio
  • Auto dimensions - Uses source image sizes and a safe browser canvas limit to choose export dimensions
  • Ratio presets - Auto, square, portrait, landscape, and photo ratios
  • Manual divider edits - Drag shared row and column dividers while keeping a clean rectangular layout
  • Undo and redo - Step back through divider changes and regenerated layouts
  • Viewer zoom - Use the preview controls or mouse wheel to inspect details
  • Drag panning - Drag inside the preview to move around when zoomed in
  • Fit modes - Fill tiles with cropping or fit full images with background padding
  • Saved options - Layout, export, and preview settings load again next time
  • Local export - Render PNG, JPG, or WebP entirely in the browser

Layout Algorithm

The tool uses a row-partition layout scorer. It reads each image’s dimensions, converts them into aspect ratios, and tries practical output ratios. For each candidate ratio, it groups images into rows, estimates how much each row would need to stretch or crop, and scores the result for crop pressure, row balance, and awkward single-image rows.

For Auto mode, the scorer tests common collage ratios plus ratios inferred from the input set. For fixed ratio modes, it keeps the requested output shape and chooses the best row grouping inside that shape.

Editing Model

Manual edits move shared dividers instead of allowing arbitrary overlapping tiles. That keeps the collage exportable as one clean rectangle and makes undo reliable. The undo history stores layout geometry only, not image data, so edits remain lightweight even with large files.

The preview area can be zoomed up to 600% with the mouse wheel or the plus, minus, and reset controls. Wheel zoom follows the cursor position, and dragging inside the preview pans around the canvas. Zoom and pan only change the viewer; they do not change the exported collage dimensions.

Code Structure

src/pages/tools/image-collage-maker.astro     -> Page with SEO
src/components/image-collage/
  ImageCollageMakerTool.tsx                   -> React UI, divider editing, export
  ImageCollageMakerTool.module.css            -> Range and preview background styling
  preferences.ts                              -> Local storage defaults and sanitization
src/lib/image-collage.ts                      -> Layout scoring and geometry helpers

Privacy & Security

All images stay on your device. The browser reads files through the File API, creates local object URLs for preview, and renders the final collage to an in-memory canvas. Nothing is uploaded to a server.

FAQs

Why are some images cropped?

The default Fill mode crops images to remove empty space and create a dense collage. Switch Image fit to Fit if you prefer to preserve every full image with background padding.

How are output dimensions chosen?

The tool starts from the total source image pixel area, caps it to a safe browser canvas budget, then applies the selected output ratio. This avoids surprising tiny exports while reducing the chance of browser memory issues with very large image sets.

Why can I only drag shared dividers?

Shared dividers preserve a rectangular grid. Freeform resizing can create overlaps, holes, or export artifacts, especially after undo and ratio changes.